Metal protectors are used to avoid corrosion of metals during their manufacture, storage, and transportation. Metal parts or surfaces must be degreased prior to subsequent metal processing operations. Over the past few years, major efforts have been made on the development of greener solvents as alternatives to chlorinated solvents such as trichloroethylene as degreasing agents in metal surface processing.
Several nitrogen-containing solvent compositions derived from natural fatty acids have recently been proposed as alternatives to chlorinated-based solvent compositions for degreasing metal surfaces (J. Bigorra, J. Raya, R. Valls, C. Estévez, L. Galià and J. Castells, EP 08 007 673.0, 2008 (Cognis/IUCT). While these solvents are as efficient as trichloroethylene in terms of degreasing efficacy, they also display intrinsic low VOC emission potential and a much better environmental, health and safety profile.
The present inventors have developed new nitrogen-free solvent compositions derived from levulinic acid. Levulinic acid can be obtained from a wide range of feedstocks including sucrose, starch, and lignocellulose. The preparation of levulinic acid from carbohydrates by the action of mineral acids is known from G. J. Mulder, J. Prakt. Chem. 21, 219 (1840), cited in U.S. Pat. No. 5,189,215. However, poor yields of levulinic acid are obtained (<25%) due to the formation of formic acid and other by-products, which reduce significantly the selectivity of the reaction. Recent technological advancements have circumvented the yield and selectivity problem and provide cost-effective technologies to manufacture cheap levulinic acid at large scale. For example, Fitzpatrick et al. (U.S. Pat. No. 4,897,947) disclose a method of degrading lignocellulose to furfural and levulinic acid. Ghorpade, et al. (U.S. Pat. No. 5,859,263).
More particularly, the present invention intends to replace commercial degreasing solvents known in the market by new compositions which are more efficient, safer and friendlier to the environment, and allow to perform metal degreasing operations in highly variable settings, with metal surfaces of different size and shape, minimizing diffuse emission, release of contaminated air during loading and unloading, and solvent release from cleaned metal surfaces.
Hernando Guerrero et al, in “PpT Behaviour of Several Chemicals from Biomass”, ENERGY FUELS, Vol. 25, no 7, 6 Jun. 2011, pages 3009-3013, discloses the study of physicochemical properties of several presumably solvents with the provision of pressure-density-temperature data. Among them ethyl levulinate and butyl levulinate are cited but there is no mention nor suggestion that these compounds can behave as a degreasing composition nor even as a solvent. Results and discussion of this document do not lead to any conclusion about the industrial application for these compounds.
WO2011/107712 relates to a method for synthesising a composition including at least one biomass-derived acid ester and an organic biosolvent. Said method is carried out by reacting at least one biomass-derived acid and at least one alcohol in the presence of an acid catalyst and the organic biosolvent finally obtaining a mixture of ester and biosolvent. None of the examples shown employ levulinic acid so as to obtain the corresponding ester and no intended use as a degreasing composition is mentioned or suggested for the levulinic acid ester employed. Additionally, the product obtained with said synthesis is a mixture of compounds.
A first object of the present invention is to provide greener solvents for degreasing metal surfaces.
A second object of the present invention relates to a process for degreasing metal surfaces using the composition of the present invention.
A third object relates to the use of a composition of the present invention for degreasing metal surfaces.